1. Field of the Invention
The present invention is related to microkeratome blade holders and blade assemblies for use in microkeratomes. More specifically, the present invention is directed to a stepped blade holder for more easily assuring that a microkeratome blade assembly is properly loaded into a microkeratome before use during surgery.
2. Description of Related Art
Microkeratomes and their associated blade assemblies and blade holders are well-known in the art. Microkeratomes include the Hansatome™ and the XP Microkeratome™ both, of which are sold by Bausch & Lomb Incorporated, the assignee of the present invention. U.S. Pat. No. 6,051,009 entitled Automatic Surgical Device for Cutting a Cornea and a Cutting Blade Assembly and Control Assembly, and U.S. Patent Publication No. 2004/0236358 entitled Bar-Link Drive System for a Microkeratome both describe microkeratomes and related microkeratome blade assemblies and both are incorporated in their entirety herein.
Blade holders are typically a structure attached to a metal, ceramic, or plastic cutting blade. The blade holder and the attached cutting blade form a blade assembly that fits within mating structure of the microkeratome. The blade holder typically cooperates with an eccentric drive-pin via a drive slot formed in the blade holder. The drive-pin, properly positioned within the drive slot, then oscillates the blade assembly during operation of the microkeratome, as it is passed across the cornea of a patient's eye during surgery, to form a corneal flap, such as for LASIK surgery. The oscillation of the blade during movement of the blade assembly across the cornea of a patient's eye is important in order to effectively and efficiently cut the cornea of the patient's eye; therefore, the seating or placement of the eccentric drive-pin in the drive slot of the blade holder is particularly important to ensure that the blade is oscillated.
Prior art blade assemblies described in the above-referenced patents and in other known microkeratomes, are effective in oscillating the blade assembly and safely and efficiently cutting a cornea during surgery, if the microkeratome blade assembly is properly placed within the microkeratome and the drive slot is properly engaged with the drive-pin of the microkeratome.
In rare circumstances, the blade assembly may not be properly loaded into the microkeratome, and a user through inattention or some other mistake may not fully place the blade assembly within the microkeratome. This may prevent the drive-pin from being engaged with the drive slot of the blade holder. If this occurs, serious complications could result and an improper flap may be formed or other damage not intended could be done to a patient's cornea.
U.S. Pat. No. 6,165,189 entitled Microkeratome for Performing LASIK Surgery discloses a conical counter sink in an upper surface of a sled. This counter sink may allow for easier engagement with an eccentric drive-pin but the sled must still be placed well into the microkeratome before the counter sink would be effective.
Therefore, there is a need for an improved blade holder and blade assembly that will ensure that the blade assembly becomes engaged with the drive-pin properly, so that the safety and effectiveness of the microkeratome during surgery may be increased.